evolution 1

WHAT IS EVOLUTION?

• Change over time.

evolution 2

WHAT IS BIOLOGICAL EVOLUTON?

•  Changes in the genetic makeup of a population of organisms over time !

evolution 3

A FACT

•  Biological organisms evolve

evolution 4

A FACT

•  Biological organisms evolve

evolution 5

A FACT

•  Biological organisms evolve •  The details are under discussion

evolution 6

ANOTHER FACT

•  Nature does not have a plan; it is more like a blind watch maker

evolution 7

WHAT IS ADAPTATION?

Def’n - properties of an organism that allow it to survive and reproduce.

evolution 8

ANOTHER FACT

•  At present, evolutionary theory is the ONLY unifying theory in biology

evolution 9

WHAT IS A THEORY?

•  A coherent system of general propositions.

evolution 10

FATHERS OF THEORY OF NATURAL SELECTION

•  Charles Darwin •  Alfred Russell Wallace •  Patrick Matthew

evolution 11

THEORIES GET ACCEPTED AS A FUNCTION OF:

•  Supporting evidence •  Current views on the matter

evolution 12

DEFINING SPECIES

Def’n - a group of actual or potentially interbreeding organisms

evolution 13

REMEMBER:

•  When we speak of evolution, we mean change across but not within generations. The latter is referred to as ontogeny.

From The World Book (TM) Multimedia Encyclopedia (c) 1999 World Book, Inc., 525 W. Monroe, Chicago, IL 60661. All rights reserved. �"World Book illustration by Richard Lewington, The Garden Studio, London �

From The World Book (TM) Multimedia Encyclopedia (c) 1999 World Book, Inc., 525 W. Monroe, Chicago, IL 60661. All rights reserved. �"World Book illustration by Richard Lewington, The Garden Studio �

1952 1990

evolution 14

DARWINIAN DEFINITION OF EVOLUTION:

•  Def’n - Descent with modification.

evolution 15

THE FIVE STAGES OF EVOLUTIONARY BIOLOGY

•  Pre- Darwinian •  Darwinian •  Eclipse of Darwin •  Modern Synthesis •  Post-Modern

evolution 16

LAMARCK’S TRANSFORMATION THEORY

Species changed due to :

•  “Programmed” internal forces •  Acquired characteristics

17

LAMARK’S INTERNAL FORCES THEORY

Trait Value

sp 1

sp 2

time

evolution 18

LAMARCK’S INHERITANCE OF ACQUIRED CHARACTERS

•  Effects of unique events get passed on to offspring.

evolution 19

CUVIER’S APPROACH

•  Whole species were frequently wiped out by catastrophe and then, miraculously, new ones appeared

evol_2 20

DARWIN’S VOYAGE 1831-6

evol_2 21

UNDENIABLY SIMILAR

GALAPAGOS MOCKINGBIRDS

evol_2 22

evol_2 23

GALAPAGOS FINCHES

evol_2 24

ONE GREAT IDEA!

•  Various finches evolved from a common ancestor

evol_2 25

FROM HIS READINGS, DARWIN KNEW

•  Earth is very old - lots of time for change •  Enormous reproductive potential for

organisms - why aren’t we covered in flies?

•  Extant variation can be selected artificially

evol_2 26

A QUOTE:

•  “… Darwins’ view of Nature… kept faith with the competitive, capitalist, Malthusian dynamics of a poor-law society and that his theory would make him an ally of the middle and upper class “

evol_2 27

A PROPOSAL

•  When together in a habitat, two similar species do better when each specializes on different resources

Beak Size

Seed

Size

evol_2 28

EVIDENCE FROM FINCHES

•  Compare alone vs. shared

evol_2 29

STICKLEBACKS

•  They come in different shapes and sizes

SHALLOW

DEEP

evol_2 30

INTERESTING PATTERN

•  When alone in lakes each species is intermediate in size

•  When together in lakes each species displays much more size extremes - benthic species is much bigger and feeds deep and the limnetic species is smaller and feeds shallow

•  Coincidence?

evol_2 31

IS BEING EXTREME BENEFICIAL?

evol_2 32

HOW THE STONEFLY GOT ITS WINGS

evol_2 33

MISSING LINK?

evol_2 34

WEISMANN SHOWED

•  Acquired characters are NOT heritable

evol_2 35

THE BIG PROBLEM:

•  Linking Mendelian inheritance to natural levels of within-population variability

evol_2 36

LEADERS OF THE MODERN SYNTHESIS

•  R. Fisher •  J. Haldane •  S. Wright

From The World Book (TM) Multimedia Encyclopedia (c) 1999 World Book, Inc., 525 W. Monroe, Chicago, IL 60661. All rights reserved. �"World Book illustration by Shirley Hooper, Oxford Illustrators Limited �

evol_3 37

BIG ACHIEVEMENT

•  Demonstration that it was that it was mathematically possible to achieve everyday patterns of variation without having to resort to acquired characteristics or hopeful monsters

evol_3 38

INDUSTRIAL MELANISM

• 

evol_3 39

POST-MODERN FEATURES

•  Demonstration of inheritance mechanism (birth of molecular biology)

•  Better integration of evolutionary and ecological theory

•  Studies on the adaptive nature of behavior (in the broad sense)

•  Studies on phenotypic plasticity •  The species concept

evol_3 40

SCPECIES CONCEPT

•  OLD - A set of similar organisms (measured against some time)

•  NEW - A group of interbreeding organisms

evol_3 41

DARWIN’S THEORY IS ELEGANT

•  It requires no demons to make it work!

evol_3 42

A SUMMARY OF DARWIN’S THEORY

•  Organisms have enormous repro. potential •  Their full potential isn’t being met •  All populations contain variants •  Some variants outperform others •  If variation is heritable, they leave more

offspring and become more common •  Given enough time, new species can arise

evol_3 43

DARWIN’S ALGORITHM

•  Substrate neutrality •   Underlying mindlessness •   Guaranteed results.

evol_3 44

ALWAYS REMEMBER:

•  Can’t have evolution by Natural Selection without variation

•  Can’t have evolution by Natural Selection without variation being heritable

•  Natural Selection works on existing variation i.e. it is not progressive

45

THOUGHT EXPERIMENT 1:

SELECT FOR SIZE

NO VARIATION - NO EVOLUTION!!

46

THOUGHT EXPERIMENT 2:

SELECT FOR SIZE

NO HERITABILITY - NO EVOLUTION!!

HIGH MEDIUM LOW

10 3 0

47

THOUGHT EXPERIMENT 3:

SELECT FOR SIZE

NO CONSISTANCY - NO EVOLUTION!!

HIGH MEDIUM LOW

10 3 0

48

THOUGHT EXPERIMENT 4:

SELECT DE NOVO FOR PATTERN

NO PROGRESSIVE EVOLUTION!!

CURRENT STOCK GOAL